[Ralph]

I guess my heater core is plugging up possibly because it sits alot and it wasn't winter driven until last year for the first time. (moderately, I might add) It's taking a long time to get any heat.

The coolant was changed a few years ago with the long life orange stuff, I added the supplemental tablets last year. I think even in the summertime, I'll occasionally run the heater to keep coolant flowing through the core to possibly help prevent sediment from plugging it. Just like how I run the AC for 5 minutes a month in winter to help keep the AC seals conditioned from lack of use as recommended in the Chilton's service manual.

I don't know if the "T" fitting can plug up or not but its never been touched.